Hydraulic pressure controlling device for intensifying cylinder

ABSTRACT

A relay piston for driving a pneumatic pressure controlling device for a servo motor is disposed at a position where it is displaced by hydraulic pressure in a low-pressure chamber connected to a master cylinder. A high-pressure chamber is formed in communication with the low-pressure chamber through a passage in the relay piston, the high-pressure chamber being connected to an intensifying cylinder. In the passage there is provided a valve adapted to intercept communication between the highpressure chamber and the low-pressure chamber in accordance with advancement of the relay piston. The force that is applied to the relay piston by hydraulic pressure in the high-pressure chamber, when the valve is closed, is the resultant of the force component acting to advance the relay piston which is greater than the force component acting to let the relay piston move forwardly.

United States Patent [191 Mochizuki et al.

Filed: Nov. 10, 1971 Appl. No.: 197,350

Foreign Application Priority Data Nov. 13, 1970 Japan 45/99478 u.s. c|... 60/575, 157/6275 Int. Cl Fl5b 7/00, Fl7d Field of Search 60/54.4 P, 54.6 P; 137/508, 627.5

References Cited UNITED STATES PATENTS 5/1962 Knowles 60/54.5 P 12/1970 Mochinzuki 60/54.6 P 4/1972 Mochizuki 60/546 P 2/1963 Beatty 60/54.6 P

FOREIGN PATENTS OR APPLICATIONS 9/1964 Great Britain 137/508 Aug. 28, 1973 Primary Examiner-Martin P. Schwadron Assistant ErWWiZWT-K: M- esi Attorney-Eric H. Waters, John G. Schwartz et a1.

[57] ABSTRACT A relay piston for driving a pneumatic pressure controlling device for a servo motor is disposed at a position where it is displaced by hydraulic pressure in a lowpressure chamber connected to a master cylinder. A high-pressure chamber is formed in communication with the low-pressure chamber through a passage in the relay piston, the high-pressure chamber being connected to an intensifying cylinder. In the passage there is provided a valve adapted to intercept communication between the high-pressure chamber and the lowpressure chamber in accordance with advancement of the relay piston. The force that is applied to the relay piston by hydraulic pressure in the high-pressure chamber, when the valve is closed, is the resultant of the force component acting to advance the relay piston which is greater than the force component acting to let the relay piston move forwardly.

7 Claims, 4 Drawing Figures l3 3 /5 /0 l4 2 l2 6 as a 36 Patented Aug. 28, 1973 3,754,395

Fig.5

2 Sheets-Sheet ,3

HYDRAULIC PRESSURE CONTROLLING DEVICE FOR INTENSIFYING CYLINDER BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to improvements in a controlling mechanism for an intensifying cylinder adapted to close or open a passage for flow of working liquid between a master cylinder and an intensifying cylinder in a braking system for vehicles.

2. Description of the Prior Art The conventional controlling devices of this type are attached to an intensifying piston or a follower part thereof so as to open or close the passage of working liquid, and they have the shortcoming that the intensifying piston and cylinder are elongated and their mounting positions are limited in relation to operation of the intensitying piston.

SUMMARY OF THE INVENTION A primary object of the present invention is to provide an improved hydraulic pressure controlling mechanism for intensifying cylinders which enables diminution of the required length of the intensifying piston and cylinder to accommodate mounting thereof substantially at any desired location and which operates positively to open the valve at the time of return to inoperative position on interruption of the servo motor or improper operation thereof while also achieving reduction of the diameter of the diaphragm in the pneumatic pressure controlling mechanism.

The hydraulic pressure controlling mechanism for an intensifying cylinder according to the present invention is separate from the intensifying piston in the intensifying cylinder and only needs to be hydraulically connected to the intensifying cylinder, so that wide choice is allowed for its mounting position. Also, the device can dispense with the control valve portion in the intensifying piston to permit corresponding reduction of the length of the intensifying piston and cylinder. The present device also features an arrangement in which the effective pressure-receiving area to move the relay piston in the backward direction when exposed to hydraulic pressure in the high-pressure chamber, is larger than the effective pressure-receiving area to move the relay piston in the forward direction when exposed to hydraulic pressure in the high-pressure chamber. Thus, at the time of return to inoperative condition on stoppage of the servo motor or trouble therein, a force is developed acting to return the relay piston by the hydraulic pressure in the high-pressure chamber. This insures positive opening of the valve in the passage between the low and high pressure chambers at such time. Further, upon actuation of the mechanism, a force tending to retract the relay piston is developed by hydraulic pressure in the high pressure chamber to act as part of the reaction against the actuating force, i.e., stepping on the brake pedal. This permits reducing the diameter of the diaphragm in the pneumatic pressure controlling mechanism for the servo motor.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of an assembly in which a hydraulic pressure controlling mechanism for an intensifying cylinder is associated with a pneumatic pressure controlling mechanism for a servo motor in a unit;

FIG. 2 is a sectional view of another assembly according to the present invention where two hydraulic pressure controlling mechanisms are associated with a common pneumatic pressure controlling mechanism in a unit;

FIG. 3 diagramatically illustrates an assembly of an overall braking system employing the controlling mechanism of FIG. 1; and

FIG. 4diagrammatically shows such an assembly with the controlling mechanism of FIG. 2.

DETAILED DESCRIPTION Referring to FIG. 1, therein is shown a combined assembly of a hydraulic pressure controlling mechanism for an intensifying cylinder, generally designated by numeral l and a pneumatic pressure controlling mechanism for a servo motor, generally designated by numeral 2. The controlling mechanisms 1 and 2 are enclosed in a housing constituted by an upper shell 3, a lower shell 4 and a plug 5. The interior of the upper shell 3 defines a relay cylinder 6 within which a relay piston 7 is slidably housed. At the upper part of relay cylinder 6 there is formed a low-pressure chamber 8 which is connected, through a connecting portion 9, to a master cylinder 47 via a conduit 48. In the lower part of the relay cylinder 6 there is formed a high-pressure chamber 10 which is connected, through a connecting section 11, to an intensifying chamber of an intensifying cylinder 49 via a conduit 50. In relay piston 7 there is formed a passage 12 connecting low-pressure chamber 8 with high-pressure chamber 10. Midway in passage 12 there is formed a valve chamber 13 in which a ball valve 14 is mounted to open or close passage 12. A valve spring 15 acts on ball valve 14, to urge the same to closed position in passage 12. The ball valve 14 is normally depressed to open position against the force of the valve spring 15 by an operative rod 16 secured to the plug 5. A head member 17 of the relay piston 7 is threadedly secured to the upper part of the relay piston after the ball valve 14 and valve spring 15 have been mounted in position in the valve chamber 13, so as to constitute an integral part of the relay piston 7. Both relay cylinder 6 and relay piston 7 are varied in diameter on both sides of the high pressure chamber 10, such that they are larger in diameter in the upper part than in the lower part. Thus, the effective pressure-receiving area (in the direction of return movement of the piston) exposed to hydraulic pressure in the high pressure chamber 10 when the ball valve 14 is closed, is larger than the effective pressure-receiving area (in the direction of advancement of the piston) exposed to hydraulic pressure when the ball valve 14 is closed. Thereby, the net effective pressure-receiving area of the relay piston exposed to pressure in chamber 10 will produce a force on the piston, when valve 14 is closed, to urge the piston in the direction of return movement. Numerals 18 and 19 denote respective piston seals.

The bottom end of the relay piston 7 abuts against the head of a valve rod 20 of the pneumatic pressure controlling mechanism 2. As will be seen, the head portion of valve rod 20 extends upwardly through an opening 22 formed in the bottom end wall 21 of the relay cylinder 6 and the base portion of the rod 20 is disposed in a vacuum chamber 23. Secured to valve rod 20 is a vent pipe 24 which extends downwardly through a diaphragm 25 and connects the vacuum chamber 23 with another vacuum chamber 27 through a vent hole 26 in valve rod 20. The vacuum chamber 23 is connected via conduit 55 to a chamber in front of the servo piston in a servo motor 54 and a vacuum pump, while the vacuum chamber 27 is connected via conduit 56 to a chamber in the rear of the servo piston in the servo motor 54. The diaphragm 25 is held between the valve rod 20 and a spring bearing 28 and is constantly pressed upwardly by a diaphragm spring 29. Below vacuum chamber 27 there is formed an atmospheric pressure chamber 30 which is connected with the atmosphere through a vent pipe 31. Between vacuum chamber 27 and atmospheric pressure chamber 30 there is provided a vent port 32, and a poppet valve 33 adapted to open and close both vent port 32 and vent pipe 24. The valve 33 is pressed against a seat face 34 by a valve spring 35. Numeral 36 designates a guide face along which poppet valve 33 is guided in up and down movement.

The device shown in FIG. 1 operates in the following manner.

When a hydraulic pressure is generated in the master cylinder 47, such pressure is immediately conveyed into the low pressure chamber 8 to act on the relay piston 7 and move it downwardly against the opposing force of the diaphragm spring 29, thereby releasing the pressure on the ball valve 14 by the operative rod 16 to allow the ball valve to move into pressed engagement against the head member 17 by the action of the valve spring 15. Thus, the high pressure chamber is closed off from the low pressure chamber 8 so that should high hydraulic pressure be generated in the intensifying cylinder 49 with operation of the servo motor 54 and intensifying cylinder 49, such pressure never leaks to the master cylinder side.

As the relay piston 7 moves down, the valve rod 20 and vent pipe 24 are also moved downward in correspondence by the descending piston 7, and first the bottom end of the vent pipe 24 comes into contact with the poppet valve 33 to shut off communication between both vacuum chambers 23 and 27, and then the poppet valve 33 is moved downward along the guide face 36 against the opposing force of the valve spring 35. This opens the vent port 32 to provide communication between the atmospheric pressure chamber 30 and the 'vacuum chamber 27. This causes a rise of pressure in the vacuum chamber 27 and actuates the servo motor 54 to generate a high hydraulic pressure in the intensifying cylinder 49. The reaction force that acts as the rebound pressure of the brake pedal 51 at the time of actuation of the servo motor is composed of a force produced due to the difference in pressure between the vacuum chambers 23 and 27 and a force produced due to the difference in diameter between the upper and lower parts of the relay piston 7. Since the effective pressure-receiving area in the return direction (upwards) is larger than that in the forward direction, as previously stated, the forces provided by hydraulic pressure in the high pressure chamber 10 act on the relay piston 7 to provide a net force that acts in the return direction, and this force serves as the rebound pressure of the brake pedal 51. Therefore, it will be understood that the reaction force for rebound pressure produced by the difference in pressure between the vacuum chambers 23 and 27 can be reduced by the amount of the reaction force produced by hydraulic pressure in the high pressure chamber 10. This means that the diameter of the diaphragm 25 can be diminished as such without loss of rebound force.

As the hydraulic pressure in the master cylinder decreases, the relay piston 7 is returned to the position shown in FIG. 1 by the action of the diaphragm spring 29, and accordingly the ball valve 14 is depressed by the operative rod 16 to open the passage 12. Consequently, the high pressure chamber 10 is communicated with the low pressure chamber 8 to allow flow of the working liquid from the intensifying cylinder to the master cylinder. In the meantime, the valve rod 20 and vent pipe 24 are also returned to their original positions with the return of the relay piston 7. As the poppet valve 33 is also returned, the servo motor and the intensifying cylinder are accordingly returned to the original positions.

If hydraulic pressure in the master cylinder 47 is raised in the event of inactivation of the servo motor 54 because of its interruption or some trouble, the relay piston 7 moves forward to release the ball valve 14 from depression by the operative rod 16 and allow the valve to abut against the head member 17. But, as the intensifying cylinder stays inoperative, hydraulic pres sure in the high pressure chamber 10 remains low, so that hydraulic pressure in the master cylinder is conducted into the high pressure chamber 10 through the low pressure chamber 8 and a space between the ball valve 14 and the head member 17. The hydraulic pressure is further transmitted from high pressure chamber 10 to the intensifying chamber and then to a wheel cylinder 52 via conduits 50 and 53 to secure at least a minimum braking force. As hydraulic pressure in the master cylinder decreases, hydraulic pressure in the low pressure chamber 8 is also lowered while hydraulic pressure in the high pressure chamber 10 is retained high as it is kept closed off by the ball valve 14, but since a force in the return direction produced in the relay piston 7 by hydraulic pressure in the high pressure chamber 10 is added to the force of the diaphragm spring 29, the relay piston 7 is strongly pushed up while the ball valve 14 is forced down by the operative rod 16, thus opening the passage 12.

In use of the present invention, it may be embodied not only in an assembly in which the hydraulic pressure controlling mechanism 1 for the intensifying cylinder and the pneumatic pressure controlling mechanism 2 for the servo motor are combined together to constitute an integral unit as shown in FIGS. 1 and 3, but also in an assembly of two or more sets of hydraulic pressure controlling mechanisms 37, 38 for the intensifying cylinder and one pneumatic pressure controlling mechanism 39 as shown in FIG. 2. In the latter embodiment, the bottom projections of the relay pistons 40 and 41 of the hydraulic pressure controllingmechanisms 37 and 38 extend through openings 42 and 43, respectively, formed in the bottom end walls of the respective relay cylinders and abut against valve rod 44. At the top end of valve rod 44 there is provided a guide stem 45 which is slidably fitted in a corresponding guide slot 46 to allow proper vertical movement of the valve rod 44. The embodiment of FIG. 2 is employed as shown in FIG. 4 where the operation is satisfactory with only one pneumatic system 54 while using two or more hydraulic systems in combination, i.e. tandem master cylinder 57 and tandem intensifying cylinder 58 each hydraulic system individually operating with the pneumatic system.

What is claimed is:

1. A hydraulic pressure controlling mechanism, said mechanism comprising a low pressure chamber connected to a master cylinder and a high pressure chamber connected to an intensifying cylinder, a relay piston extending in both chambers for slidable displacement therein in forward and return directions, a pneumatic pressure controller for a servo motor which operates the intensifying cylinder, said pressure controller including means acted on by said piston for controlling operation of the servo motor, said relay piston being so disposed in the low pressure chamber such that the piston is displaced in forward direction by hydraulic pressure in said low pressure chamber, said relay piston having a passage therein providing communication between said high pressure chamber and said low pressure chamber, and a valve means in said passage for selectively intercepting communication between said high pressure chamber and said low pressure chamber in accordance with advancement of said relay piston in the forward direction, said relay piston having a first effective pressure-receiving area and a second effective pressure receiving area, the latter being larger than the former, both of said areas being exposed to pressure in the high pressure chamber such that a net force is applied to the relay piston to urge the relay piston in return direction.

2. A mechanism as claimed in claim 1, in which said relay piston has opposite ends, said low pressure chamber being formed adjacent one of the ends of the relay piston and said high pressure chamber being formed in the middle of said relay piston.

3. A mechanism as claimed in claim 2 wherein avalve chamber is provided in the passage connecting said low and high pressure chambers with each other, said valve means comprising a ball valve in said valve chamber and a valve spring acting on said ball valve in a direction to close said passage, and a stationary operative rod facing said ball valve to push said ball valve in a direction to open said passage when the relay postion assumes a normal inoperative position.

4. A mechansim as claimed in claim 1 in which said means of said pressure controller which is acted on by said piston includes a valve rod controlling pneumatic pressure for the servo motor, said relay piston having a forward end positioned in abutment with said valve rod.

5. A mechanism as claimed in claim 1 comprising a second of said relay pistons, both relay pistons being operatively associated with said pressure controller through said means thereof.

6. A mechanism as claimed in claim 5 wherein said means of said pressure controller which is acted on by both relay pistons includes a valve rod controlling pneumatic pressure for the servo motor, said relay pistons being positioned in abutment with said valve rod for individual operation therewith.

7. A mechanism as claimed in claim 1 comprising a common housing enclosing said chambers, said relay piston, and said pneumatic pressure controller. 

1. A hydraulic pressure controlling mechanism, said mechanism comprising a low pressure chamber connected to a master cylinder and a high pressure chamber connected to an intensifying cylinder, a relay piston extending in both chambers for slidable displacement therein in forward and return directions, a pneumatic pressure controller for a servo motor which operates the intensifying cylinder, said pressure controller including means acted on by said piston for controlling operation of the servo motor, said relay piston being so disposed in the low pressure chamber such that the piston is displaced in forward direction by hydraulic pressure in said low pressure chamber, said relay piston having a passage therein providing communication between said high pressure chamber and said low pressure chamber, and a valve means in said passage for selectively intercepting communication between said high pressure chamber and said low pressure chamber in aCcordance with advancement of said relay piston in the forward direction, said relay piston having a first effective pressure-receiving area and a second effective pressure receiving area, the latter being larger than the former, both of said areas being exposed to pressure in the high pressure chamber such that a net force is applied to the relay piston to urge the relay piston in return direction.
 2. A mechanism as claimed in claim 1, in which said relay piston has opposite ends, said low pressure chamber being formed adjacent one of the ends of the relay piston and said high pressure chamber being formed in the middle of said relay piston.
 3. A mechanism as claimed in claim 2 wherein a valve chamber is provided in the passage connecting said low and high pressure chambers with each other, said valve means comprising a ball valve in said valve chamber and a valve spring acting on said ball valve in a direction to close said passage, and a stationary operative rod facing said ball valve to push said ball valve in a direction to open said passage when the relay postion assumes a normal inoperative position.
 4. A mechansim as claimed in claim 1 in which said means of said pressure controller which is acted on by said piston includes a valve rod controlling pneumatic pressure for the servo motor, said relay piston having a forward end positioned in abutment with said valve rod.
 5. A mechanism as claimed in claim 1 comprising a second of said relay pistons, both relay pistons being operatively associated with said pressure controller through said means thereof.
 6. A mechanism as claimed in claim 5 wherein said means of said pressure controller which is acted on by both relay pistons includes a valve rod controlling pneumatic pressure for the servo motor, said relay pistons being positioned in abutment with said valve rod for individual operation therewith.
 7. A mechanism as claimed in claim 1 comprising a common housing enclosing said chambers, said relay piston, and said pneumatic pressure controller. 